1. Field of the Invention
The present invention relates to a mobile terminal apparatus, and more particularly, to a mobile terminal apparatus with an easy design layout, a bidirectional optical communication between a fixed part and a moving part of a housing, a compact size, an increased reliability, and a signal-line noise rejection.
2. Description of the Related Art
FIG. 11 is a block diagram of a conventional mobile terminal apparatus. FIG. 12 is a perspective view of a hinge part of the conventional mobile terminal apparatus. FIG. 13 is an exploded perspective view of the hinge part.
As shown in FIGS. 11 to 13, the conventionally mobile terminal apparatus of a flip type includes a fixed part (fixed housing) 1 and a moving part (moving housing) 3 that contain various types of mounted devices 1a, 3a for various functions of the mobile terminal apparatus, as well as a plurality of circuit devices (not shown). The fixed part 1 and the moving part 3 are linked via a pair of hinge parts 2 in an openable and closable manner.
The mounted devices la in the fixed part 1 include keys used for various input operations and a central processing unit (CPU) for performing numerical and logical computations. The mounted devices 3a in the moving part 3 include, for example, a liquid crystal display (LCD), a speaker, an imaging device, an IrDA device, an status sensor, a light sensor, a TV tuner, a radio tuner, and a light emitting diode (LED).
The fixed part 1 and the moving part 3 incorporate their respective circuit boards (not shown) for providing functionality for the mounted devices 1a, 3a. Because a bidirectional signal transmission is required, a connection is established between the boards via the hinge parts 2 using, for example, a flexible board or a wire bundle 4 and connectors 5.
As shown in FIGS. 12 and 13, the fixed part 1 and the moving part 3 are linked via the pair of hinge parts 2, which are formed to allow swing motion by inserting hinge shafts 8 into insertion holes 21 in bearing members 20a, 20b. The fixed part 1 includes insertion holes 22. The moving part 3 includes stopper parts 23 for limiting positions of the hinge shafts 8 in the bearing members 20b. 
The related conventional technology is disclosed in Japanese Patent Application-Laid-Open No. H10-97346, Japanese Patent Application-Laid-Open No. 2002-157046, and Japanese Patent Application-Laid-Open No. 2005-64843.
In the conventional mobile terminal apparatus shown in FIGS. 11 to 13, however, interface signals between the boards are electrically connected using, for example, the flexible board or wire bundle 4, which can cause various problems as described below.
Because the mobile terminal apparatus is opened and closed repeatedly and the flexible board or wire bundle 4 moves together with the hinge parts 2, a failure may happen, such as a break of signal lines due to an external force from bending, twisting, and pulling of the flexible board or wire bundle 4.
At a manufacturing process, a connection is established via the connectors 5 between the flexible board or wire bundle 4 and boards (not shown) disposed in the fixed part 1 and the moving part 3. Because the connection process is manually performed, manufacturing defects tend to occur, including a poor contact in the connectors 5.
The flexible board or wire bundle 4 must be contained in the hinge parts 2, and therefore securing of room for mounting the flexible board or wire bundle 4 becomes a stumbling block for a reduction of a size of the mobile terminal apparatus.
Furthermore, because the boards (not shown) are connected using the flexible board or wire bundle 4, routing of the signal lines becomes long, which results in an increase of a resistive component and capacitive component that can cause a signal degradation.
In the connection between the boards using the flexible board or wire bundle 4, signals propagate through board→connector→flexible cable (long signal line)→connector→board. This causes a greater impedance change or a larger noise emission due to the routing of the signal lines.
In the conventional technologies disclosed in the first and the second literatures, although the mobile terminal apparatus supports an optical communication of display data, only a unidirectional communication from the fixed part to the moving part can be implemented.
In a mobile terminal apparatus according to the present invention, a bidirectional data communication is required because it is assumed that a moving part contains the mounted devices, including an LCD, a speaker, an imaging device, an IrDA device, a status sensor, a light sensor, a TV tuner, and a radio tuner, as in the conventional mobile terminal apparatus described above. Therefore, the conventional technologies disclosed in the first and the second literatures cannot be applied as they are.
In the conventional technology disclosed in the third literature, two housings disposed in an overlapped manner are linked by a linking unit so as to be mutually swingable around an axis extending in a lap direction. Although the bidirectional optical communication is enabled, the structure is different from that of the mobile terminal apparatus of the flip type described above.
In other words, each of the fixed part and the moving part has a light emitting unit and a light receiving unit so that they face each other with their optical axes aligned, and that the axes are disposed in the thickness directions of the sections. Therefore, the optical axes are always aligned, regardless of the relative positions (swing positions) of the fixed part and the moving part.
However, in the mobile terminal apparatus of the flip type (see FIG. 12), the hinge shafts 8 in the hinge parts 2 are disposed in a direction orthogonal to the thickness direction of the fixed part 1. In a design layout, limited space makes it difficult to place a light emitting unit and a light receiving unit to face each other, concentrically with the hinge shafts 8 so as to align their optical axes.